Preparation of dihydroxyalkyladamantanes



United States Patent Ofilice 3,356,741 Patented Dec. 5, 1967 3,356,741 PREPARATION OF Dll-IYDRGXYALKYL- ADAMANTANES Abraham Schneider, Over-brook Hills, Pa., assignor to Sun Oil Company, Philadelphia, Pa, a corporation of New Jersey No Drawing. Filed Sept. 10, 1964, Ser. No. 395,580 17 Claims. (Cl. 260-617) This invention relates to the preparation of diols from alkyladamantanes of the C -C range which have at least two unsubstituted bridgehead positions. More specifically the invention pertains to the formation of 1,3-dihydroxyalkyladarnantanes by oxidizing by means of a free oxygen-containing gas alkyladamanates of the following class: methyladamantane, ethyladamantane, dimethyladamanatane and methylethyladarnantane. The invention also embraces the conversion of monohydroxyalkyladamanates to the corresponding bridgehead dihydroxy derivatives by oxidation.

The carbon nucleus of adamantane (tricyclo[3.3.1.1 decane) contains ten carbon atoms arranged in a completely symmetrical, strainless manner such that four of the carbon atoms occupy bridgehead positions in the rings. The structure of adamantane is often depicted typographically as follows:

All four bridgehead carbons are equivalent to each other and likewise all rings are equivalent.

In the prior art as described in J. Org. Chem., vol. 26, pages 2207-2212 (1961), adamantane itself has been oxidized by means of air to produce l-hydroxyadamantane as the principle oxidation product. No dihydroxyadamantane was identified in the reaction product. In this work a solvent for the adamantane was required, a peroxide catalyst was included in the reaction mixture and a high air pressure was utilized. More specifically, a mixture of benzene and glacial acetic acid was used as solvent, both cobalt acetate and di-t-butyl peroxide were employed together as catalysts and an air pressure of 800 p.s.i.g. was employed.

The present invention concerns the preparation of bridgehead dihydroxy derivatives of C -C alkyl substituted adamantanes, namely, methyladamantane, ethyladamantane, dimethyladamantane and methylethyladamantane. In these hydrocarbons the alkyl groups are preferably although not necessarily located at bridgehead positions, in which case the starting hydrocarbon is l-methyladamantane, l-ethyladamantane, 1,3-dimethyladamantane or 1-methyl-3-ethyladamantane. Conversion of these hydrocarbons to the corresponding bridgehead dialcohols according to the present invention is effected by oxidizing the hydrocarbon with free oxygen. The procedure does not require the use of any solvent or of a peroxide type catalyst, and high pressure is not needed to effect the oxidation.

In one aspect the invention involves oxidizing an alkyladamantane as above specified in one step, the oxidation being continued until a satisfactory yield of bridgehead dihydroxy alcohol is obtained. In this procedure the alkyladamantane is contacted in the absence of a solvent with a free oxygen-containing gas at a temperature in the range of 110-210 C. and more preferably 120-170 C. The

oxidizing gas preferably is pure oxygen in which case the pressure preferably is about atmospheric. On the other hand air can be used in which case a moderately elevated pressure such as 40-100 p.s.i.g. preferably is employed. A small amount of a soluble oxidation catalyst is used, which catalyst is an organic salt of a metal of the group consisting of cobalt, manganese, iron and magnesium. This is the sole catalytic agent used to promote the oxidation. Only more or less trace amounts of the catalyst are required such as from 0.001% to 0.2% by weight of the mixture. Considerably larger amounts (e.g., 1% or 5% or higher) can be used although no benefits will result from using excessive amounts of the catalyst. The contacting of the free oxygencontaining gas with the alkyladamantane at the specified temperature is continued until at least of the alkyladamantane has been oxidized and more preferably until at least of it has been transformed to oxidation products. By continuing the oxidation until such as advanced stage of oxidation is reached, a good yield of the bridgehead dialcohol can be obtained. The reaction mixture will also contain substantial amounts of monooxidation products, namely, the l-hydroxy derivative and the keto derivative, and it also will contain lesser amounts of other dioxidation products which consist of several hydroxyketoalkyladarnantane isomers. From the reaction mixture the 1,3-dihydroxy product can easily be separated almost quantitatively by diluting the mixture with a saturated hydrocarbon diluent such as pentane or a dialkyl ether such as diethyl ether. All reaction products except the dialcohol are soluble in such diluents and hence the 1,3-dihydroxyalkyladamantane is obtained as a separate solid phase. Also from the reaction mixture the monooxidation products, i.e., the l-hydroxy and the keto derivatives, can be separated by distillation and utilized as hereinafter described.

In the above-outline oxidation procedure the oxidation is carried in one'step to an advanced stage wherein complete oxidation of the alkyladamantane hydrocarbon is at least approached with the result that a substantial yield of the dihydroxy product is obtained. That the oxidation can be carried this far in a clean reaction and without the formation of tar or numerous other undesirable reaction products is most unusual for the oxidation of saturated hydrocarbons. When practically any other type of saturated hydrocarbon (e.g., decalin) is oxidized with free oxygen, the oxidation must be stopped far short of the advanced stage that is reached in carrying out the abovedescribed procedure in order to avoid formation of tarry material. Hence the usual procedure is to oxidize to a relatively low degree of conversion, separate the reaction products from unreacted hydrocarbon and recycle the latter to the oxidation. In the present one-step procedure the oxidation is unusual in that complete conversion of the hydrocarbon to oxidized products is approached and such products include a substantial proportion of the desired dioxidation product. This is made possible by the remarkable stability of the adamantane nucleus against carbon to carbon scission, which stability most if not all other saturated hydrocarbons lack.

In another aspect the invention involves a two-stage oxidation procedure for producing the desired bridgehead dihydroxy products. The starting hydrocarbon first is subjected to oxidation in the absence of a solvent and in the presence of a small amount of metal salt oxidation catalyst as previously specified by contacting the hydrocarbon at a temperature in the range of -210 C., more preferably -170" C., with free oxygen-containing gas. The contacting is continued only to a stage of oxidation at which the monooxidized products predominate. These products are the l-hydroxy derivative and the keto derivative. Minor amounts of dioxygenated products will also be for-med but the reaction is stopped before these predominate over the monooxidation products. For example, the oxidation reaction can be stopped when the conversion approaches 70%, i.e., when nearly 70% of the hydrocarbon charge has been converted to oxidation products, in which case the weight ratio of monooxidation to dioxidation products typically may be 8:1.

After this first stage of oxidation has been completed, the reaction mixture can be distilled to remove any unconverted alkyladamantane and further distilled to obtain a concentrate of the two monooxi-dation products. The amount of l-hydroxy derivative in this concentrate generally will be 2-3 times the amount of the keto derivative. This concentrate is then subjected to hydrogenation to convert the keto derivative to the corresponding non-bridgehead monoalcohol and the resulting mixed alcohols are then subjected to isomerization conditions under which the non-bridgehead alcohol converts to bridgehead alcohol, all as more fully described hereinafter.

The resulting l-hydroxyalkyladarnantane thus produced in admixture with say 0.005% of cobalt naphthenate is contacted at a temperature in the range of ll-2l0 C., more preferably 120170 C., with a free oxygen-containing gas to produce the bridgehead dihydroxy derivative. In effecting this second oxidation it is distinctly preferable to add a further amount of the starting alkyladamantane to the monohydroxy derivative and subject the mixture to contact with the oxygen-containing gas. The reason for this is that otherwise the l-hydroxyalkyladamantane may be in crystalline form at the reaction temperature and will tend to sublime in the reaction system. To avoid this the alkyladamantane should be added to the monohydroxy compound in amount of one part to from one to three parts of the monool. This will keep the reaction mixture fluid and prevent sublimation of the monool. During the oxidation the added hydrocarbon will convert largely to monooxidation products while the monoalcohol will convert to 1,3-dihydroxyalkyladamantane. The latter can be separated by diluting the reaction mixture with pentane or ether. The monooxidation products are then subjected to the .hydrogenation and isomerization steps previously referred to, and the resulting bridgehead monohydroxy product is then oxidized in the presence of added alkylyadamantane. Thus the procedure becomes a cyclic process by which most of the starting hydrocarbon is converted to its bridgehead dihydroxy derivative.

In still another aspect of the invention l-hydroxyalkyladamantane derived in any suitable manner is converted to the bridgehead dihydroxy compound by oxidation as described above, preferably in admixture with the alkyladamantane.

The starting alkyladamantane for practicing the present invention can be prepared by the isomerization of tricyclic naphthenic hydrocarbons having the same number of carbon atoms as the desired alkyladamantane. Such isomerization using an aluminum halide catalyst is described in Schneider United States Patent No. 3,128,- 316, and isomerization of tricyclic naphthenate using HF-BF as catalyst for producing the alkyladamantanes having an ethyl substituent is described in Janoski et al. application Ser. No. 359,401, filed Apr. 13, 1964, now Patent No. 3,275,700. The alkyladamantanes formed by these procedures mainly have the alkyl groups substituted at bridgehead positions, although minor amounts of isomers in which one or more of the alkyl groups are located at non-bridgehead positions are also produced especially if the isomerization reaction is terminated before it reaches completion. By way of example 1,3-dimethyladamantane can be made in good yield from perhydroacenaphthene by contacting the latter with a liquid Alcl -HCl-hydrocarbon complex catalyst at 35 C. for

eight hours. Again using perhydroacenaphthene, a good.

yield of l-ethyladamantane can be obtained by contacting this tricyclic naphthene with HF-BF at 85 C. for

4- six hours. As a further example a good yield of I-methyl- 3-ethyladarnantane can be obtained by contacting perhydrofluorene with HF-BF at 100 C. for eight hours.

The preferred alkyladamantanes for practicing the invention are the following in which all alkyl substituents are located at bridgehead positions: l-methyladamantane; 1 ethyladamantane; 1,3 dimethyladamantane; and 1- methyl-3-ethyladamantane. All of these have at least two bridgehead positions open so that formation of the hydroxy groups at those positions can be effected.

The catalyst for promoting the oxidation can be any organic salt of cobalt, manganese, iron or magnesium which is soluble in the starting alkyladamantane in the concentrations specified above at the reaction temperature used. The catalyst can be salt of practically any organic acid such as acetic, propionic, decanoic, oleic, stearic, naphthenic, oxalic, benzoic and toluic acids. The organic salts of cobalt and manganese are the preferred types of catalysts- Any of the oxidation steps referred to above can be carried out by blowing pure oxygen through the reaction mixture at a temperature in the range of l10- 210 C. Alternatively air can be used in which case it is desirable to use a moderately elevated pressure. Preferably such pressure does not exceed 50 p.s.i.g. in the step wherein the objective is to reach only the monooxidation stage and does not exceed 100 p.s.i.g. in oxidations in which the objective is to produce the dialcohol. It is generally preferable to oxidize at temperatures below 170 C., and in the one-step procedure for making the dialcohol it is desirable to keep the temperature below 140 C. Best selectivity for producing the dialcohol seems to be obtained at a temperature of 120-130 C.

In the embodiment of the invention in which two stages of oxidation are utilized, the following is an illustrative composition of the first stage reaction product which can be obtained when the oxidation of the alkyladamantane is carried, for example, to a conversion level:

Weight percent of product Unreacted alkyladamantane 25 l-hydroxy derivative 39 Keto derivatives l9 Hydroxyketo derivatives ll 1,3-dihydroxy derivative 6 Other 1 By diluting the reaction mixture with pentane or ether the bridgehead dialcohol can be obtained as a crystalline solid. The remaining reaction mixture can be distilled to remove the unreacted alkyladamantane and further distilled to obtain a concentrate of the l-hydroxy and the keto derivatives which have relatively close boiling points. This concentrate is then subjected to hydrogenation followed by isornerization to convert all of the keto compounds to the bridgehead monoalcohol.

Hydrogenation of the ketoalkyladarnantane can be effected in several ways. The hydrogenation can be achieved by using lithium aluminum hydride in ether or sodium borohydride in methanol at ambient temperature as the hydrogenating agent. Alternatively the hydrogenation can be done by employing Adams platinum oxide catalyst using acetic acid as solvent, ambient temperature and a hydrogen pressure of 23 atmospheres. Still another suitable procedure involves the use of Raney nickel at about 100 C. with a hydrogen pressure of about 1000 p.s.i.g. By any of these procedures the keto compounds will be converted to the corresponding secondary alcohols while the l-hydroxyalkyladamantane will be unaffected.

After the mixed alcohols are obtained by hydrogenation, the mixture is subjected to isomerization conditions so as to convert all of the non-bridgehead alcohols to the l-hydroxy derivative. This can be done by the procedure disclosed and claimed in my copending application Ser. No. 395,556, filed of even date herewith. In such proce dure the non-bridgehead alcohols are isomerized to the l-hydroxy compound by contacting the mixed alcohols with a concentrated mineral acid, viz. sulfuric acid or phosphoric acid. A weight ratio of concentrated acid to mixed alcohols in the range of 0.5 :1 to 2:1 preferably is taken at four difierent reaction times and were analyzed by vapor phase chromatography in conjunction with infrared spectra. Reaction temperatures and times and compositions of the samples are shown in Table I wherein the term DMA refers to dimethyladamantane and the reaction mixture components are listed in order of increasing boiling points.

TABLE I Sample Sample Sample Sample No. 1 No. 2 No. 3 N0. 4

Reaction temp, C 135 149-159 150 153460 Cumulative reaction time, min. 90 180 382 637 Product composition, wt. perce DMA 18.4 12.7 2.0 0.3

l-hydroxy DMA 46. 3 41. 3 29.0 23. 3

Keto DMA 14. 6 16.5 16. 5 14.6

Unknowns 1. 4 1. 9 2. 9 2. 6

1,3-dihydrxy DMA 10. 7 13. 0 22. 9 26. 4

Hydroxyketo DMA L. 4. 9 7. 14. 4 17. O

Hydroxyketo DMA II 3. 7 7.0 12. 5 15. 9

used. When employing sulfuric acid the temperature should be in the range of 0-80 0, while with phosphoric acid a higher temperature such as 100 C. should be used. The alcohols dissolve in the concentrated acid and the non-bridgehead alcohols isomerize almost immediately to the l-hydroxy product. The latter can then be recovered from the acid by dilution with water, whereby l-hydroxyalkyladamantane will be obtained as precipitate. In cases where the mixed alcohols contained some unconverted alkyladamantane, only the alcohols will dissolve in the concentrated acid and the alkyladamantane can be separated from the mixture as an insoluble phase.

The precipitated bridgehead monohydroxy product, which was formed in part in the initial oxidation step and in part in the isomerization step following hydrogenation, is preferably admixed with from one-third to an equal weight of the starting alkyladamantane and the mixture is oxidized as previously described. The oxidation of this mixture will convert the l-hydroxy compound mainly to l,3-dihydroxya1kyladamantane and the added hydrocarbon mainly to 1-hydroxyalkyladamantane.

As previously stated the bridgehead dialcohol product can be separated from all other oxidation products and any unreacted alkyladamantane that may be left in the reaction mixture by diluting the latter with a suitable diluent in which only the dialcohol is insoluble. Such diluent should be a saturated hydrocarbon of the C -C range or a dialkyl ether in which the alkyl groups have 1-4 carbon atoms. Example-s of suitable saturated hydrocarbon diluents are n-pentane, isopentane, cyclopentane, n-hexane, 2,3-dimethylbutane, methylcyclopentane, cyclohexane, n-heptane, isoheptanes, methylcyclohexane, nand iso-octanes, dimethylcyclohexane and the like. Mixtures of such hydrocarbons, such as a saturated naphtha fraction can be employed. Ethers that can be used are dimethyl ether, methylethyl ether, diethyl ether, ethylpropyl ether, diisopropyl ether, methylbutyl ether, diisobutyl ether and the like. The amount of diluent added should be suificient to cause substantially all of the dialcohol to precipitate. This generally will be in the range of 0.5 to 5 volumes of diluent per volume of reaction mixture and preferably at least 1:1. All of the other reaction products will remain in solution in the diluent.

The following examples illustrate the invention more specifically:

Example I In this example oxygen at atmospheric pressure was used to exhaustively oxidize 1,3-dimethyladamantane and produce 1,3-dihydroxy-5,7-dimethyladamantane in substantial yield in a single oxidation step. About 0.005% of cobalt naphthenate was dissolved in the hydrocarbon charge and the mixture was oxidized at temperatures in the range of 135160 C. by bubbling oxygen into the mixture while it was being vigorously stirred. Samples were The product material listed as hydroxyketo DMA I and that listed as II appeared under different peaks of the chromatograph. It is probable that each of these includes at least two hydr-oxyketone isomers having boiling points close to each other. From the tabulated data it can be seen that the bridgehead monohydroxy compound initially is formed as the major product of the reaction. Substantial amounts of the keto product also are formed. Upon continued oxidation the content of monohydroxy compound progressively decreases while the bridgehead dialcohol content continuously increases. The amount of hydroxyketo compounds also progressively increases.

The final reaction product from the foregoing oxidation run was diluted at room temperature with about two volumes of n-pentane per volume of reaction product. Upon filtration crystalline 1,3-dihydroxy-5,7-dimethyladamantane was separated in substantially quantitative amount. This compound had a melting point of 215- 216 C.

It will be noted that during the foregoing oxidation run the temperature during most of the reaction time was about l50l60 C. The use of lower temperatures will give a more selective reaction and reduce the proportions of the monoketo and hydroxyketo compounds formed. Hence it is preferable to maintain the reaction temperature in the range of l20-l30 C. to improve selectivity of the reaction for formation of the dialcohol.

Example 11 This example involves the use of two oxidation stages with hydrogenation and isomerization steps therebetween to produce the dialcohol from 1,3-dimethyladamantane. The procedure involved first blowing the charge hydrocarbon with air at about atmospheric pressure using about 0.005% of undissolved cobalt naphthenate as catalyst. The reaction temperature was maintained in the range of 166168 C. Samples were taken at three different times and analyzed as before. Table II shows the reaction temperature and times and the analyses obtained.

The final reaction product corresponding to Sample No. 3 was distilled to obtain an intermediate cut which was a concentrate of the two monoxidation products composed of about 70% 1-hydroxy DMA and 30% keto DMA. This mixture was converted to mixed DMA alcohols in the following manner. About 4.2 g. of the mixture was dissolved in 8 ml. of methanol and the solution was added dropwise to a sodium borohydride solution consisting of 1.5 g. NaBH 3 ml. of water and ml. of methanol. After refluxing the resulting mixture for 1 hr., 25 ml. of 10 N aqueous NaOH was added and refluxing was continued for 30 minutes. The mixture was then extracted four times with ether and the ether was evaporated from the combined extracts. About 4.2 g. of mixed DMA alcohols were obtained. These were dissolved in 10 g. of 96% sulfuric acid, and the solution was warmed to 50 C. for 10 minutes, then cooled and poured over ice. The precipitated monoalcohol was dissolved in diethyl ether, the solution was dried by means of Na SO and the ether was evaporated. Substantially pure 1-hydroxy-3,5-dimethyladamantane having a melting point of 94 C. was obtained.

0.50 g. of the resulting bridgehead monoalcohol was mixed with 0.90 g. of 1,3-dimethyladamantane and cob-alt acetate was added in amount of about 0.01% by weight. Oxygen was bubbled through the mixture at atmospheric pressure while maintaining a temperature of 139144 C. Samples of the reaction product were taken and analyzed as shown in Table III.

to use only from one-third volume to an equal volume of the hydrocarbon.

Substantially analogous results are obtained when 1- methyladamantane, l-ethyladarnantane or 1-methyl-3- ethyldamantane is substituted for the alkyladarnantane shown in the foregoing examples. Also generally similar results are obtained when the starting alkyladamantane contains one or more alkyl groups at non-bridgehead positions.

My copending application Ser. No. 395,557, filed of even date herewith, describes and claims the preparation of bridgehead monohydroxyalkyladamantane. In that process the oxidation is stopped before 70% of the starting hydrocarbon has been oxidized so as to avoid the formation of dioxygenated compounds. The alcohols of this invention can be used as plasticizers or as intermediates tor preparing mixed esters containing alkyladamantane moieties.

I claim:

1. Methods of preparing dihydroxyalkyladamantanes which comprises contacting an allcyladamantane selected from the group consisting of methyladamantane, ethyladamantane, dimethyladamantane and methylethyladamantane with a free oxygen-containing gas at a temperature in the range of 110-210 C. and in the presence of a small amount of oxidation catalyst consisting of a soluble 1 Includes all isomers.

The final reaction product corresponding to Sample No. 3 was diluted with twice its volume of n-pentane at room temperature. Upon filtration the 1,3-dialcohol was obtained in approximately quantitative yield. It is apparent that by distillation a concentrate of the two monooxidation products could be obtained for recycling to the above-described hydrogenation step.

Example 111 A sample of pure 1-hydroxy-3,S-dimethyladamantane to which had been added a catalytic amount of cobalt naphthenate was oxidized in the absence of any added alkyladamantane by bubbling oxygen therethrough at atmospheric pressure and maintaining a temperature of 161- 171 C. Table IV shows the results after 65 minutes of oxidation.

TABLE IV Cumulative reaction time, min 65 Product composition, wt., percent l-hydroxy DMA 75.7 1,3-dihydroxy DMA 16.7 Hydroxyketo DMA I 5.5 Hydroxyketo DMA II 2.2

hydrocarbyl carboxylic acid salt of a metal selected from the group consisting of cobalt, manganese, iron and mag nesium, continuing said contacting until at least of the alkyladamantane has been oxidized, whereby bridgehead dihydroxyalkyladamantane is formed in substantial amount, and recovering 1,3-dihydroxyalkyladamantane from the reaction mixture.

2. Method according to claim 1 wherein said contacting is continued until at least of the alkyladamantane has been oxidized.

3. Method according to claim 2 wherein said temperature is in the range of 120-170 C.

4. Methodaccording to claim 1 wherein said temperature is in the range of 120-170 C.

5. Method according to claim 1 wherein the 1,3-dihydroxyalkyladamantane is recovered by diluting the reaction mixture with a diluent selected from the group consisting of saturated hydrocarbons of the C C range and dialkyl ethers in which each alkyl group has 1-4 carbon atoms and separating the 1,3-dihydroxyalkyladamantane as a precipitate.

6. Method of preparing dihydroxyalkyladamantanes which comprises contacting an alkyladamantane selected from the group consisting of methyladamantane, ethyladamantane, dimethyladamantane and methylethyladamantane with a free oxygen-containing gas at a temperature in the range of l10210 C. and in the presence of a small amount of oxidation catalyst consisting of a soluble hydrocarbyl carboxylic acid salt of a metal selected from the group consisting of cobalt, manganese, iron and magnesium, said contacting being effected in the absence of a solvent and under a pressure less than p.s.i.g., whereby oxidation occurs to form 1-hydroxyalkyladamantane,

ketoalkyladamantane and a minor amount of higher boiling oxidation products, stopping said contacting before 70% conversion of the hydrocarbon charge and while the l-hydroxyalkyladamantane and ketoalkyladamantane are the main reaction products, separating a concentrate of the last-named products from said higher boiling oxidation products, hydrogenating said concentrate to convert the ketoalkyladamantane to non-bridgehead hydroxyalkylada mantane, isomerizing the hydrogenated concentrate by contacting said concentrate with a concentrated mineral acid selected from the group consisting of sulfuric acid and phosphoric acid to convert the non-bridgehead hydroxyalkyladamantane to its bridgehead isomer, contacting the isomerizate with a free oxygen-containing gas at a temperature in the range of 110-210 C. and in the presence of a small amount of oxidation catalyst as above specified, whereby bridgehead dihydroxyalkyladamantane is formed as the main oxidation product, and recovering l,3-dihydroxyalkyladamantane from the reaction mixture.

7. Method according to claim 6 wherein each of said temperatures is within the range of 120170 C.

8. Method according to claim 7 wherein said isomerizate is admixed with a further amount of said alkyladamantane prior to said contacting with a free oxygencontaining gas.

9. Method of preparing dihydroxyalkyladamantanes which comprises contacting the l-hydroxy derivative of an 'alkyladamantane selected from the group consisting of methyladamantane, ethyladamantane, dimethyladamantane and methylethyladamantane with a free oxygencontaining gas at a temperature in the range of l10210 C. and in the presence of a small amount of oxidation catalyst consisting of a soluble hydrocarbyl carboxylic acid salt of a metal selected from the group consisting of cobalt, manganese, iron and magnesium, whereby bridgehead dihydroxyalkyladamantane is formed as the main reaction product, and recovering 1,3-dihydroxyalkyladamantane from the reaction mixture.

10. Method according to claim 9 wherein the contacting of oxygen with said l-hydroxy derivative is done in the presence of said alkyladamantane and the latter simultaneously oxidizes to form l-hydroxyalkyladamantane as its main oxidation product.

11. Method according to claim 9 wherein the 1,3-dihydroxyalkylada-rnantane is recovered by diluting the reaction mixture with a diluent selected from the group consisting of saturated hydrocarbons of the C -C range and dialkyl ethers in which each alkyl group has 1-4 carbon atoms and separating the 1,3-dihydroxyalkyladamantane as a precipitate.

12. Method according to claim 9 wherein said temperature is in the range of -170 C.

13. Method according to claim 1 wherein said alkyladamantane is selected from the group consisting of 1- methyladamantane, l-ethyladamantane, 1,3-dimethyladamantane and l-methyl-3-ethyladamantane.

14. Method according to claim 6 wherein said alkyladamantane is selected from the group consisting of lmethyladamantane, l-ethyladamantane, 1,3-dimethy1- adamantane and 1-methyl-3-ethyladamantane.

15. Method according to claim 9 wherein said alkyladamantane is selected from the group consisting of 1- methyladamantane, 1 ethyladamantane, 1,3 dimethyladamantane and 1-methyl-3-ethyladamantane.

16. Method according to claim 9 wherein said oxygencontaining gas is pure oxygen.

17. Method according to claim 1 wherein said oxygencontaining gas is pure oxygen.

References Cited Schleyer et al.: J. Am. Chem. Soc., vol. 83, pp. 182-7 (1961) QDI A5.

Stetter et a1.: Chem. Abstracts, vol. 57, p. 5817 (1962) QDI A51.

BERNARD HELFIN, Primary Examiner. LEON ZITVER, Examiner.

T. G. DILLAHUNTY, Assistant Examiner. 

1. METHODS OF PREPARING DIHYDROXYALKYLADAMANTANES WHICH COMPRISES CONTACTING AN ALKYLADAMANTANE SELECTED FROM THE GROUP CONSISTING OF METHYLADAMANTANE, ETHYLADAMANTANE, DIMETHYLADAMANTANE AND METHYLETHYLADAMANTANE WITH A FREE OXYGEN-CONTAINING GAS AT A TEMPERATURE IN THE RANGE OF 110-210*C. AND IN THE PRESENCE OF A SMALL AMOUNT OF OXIDATION CATALYST CONSISTING OF A SOLUBLE HYDROCARBYL CARBOXYLIC ACID SALT OF A METAL SELECTED FROM THE GROUP CONSISTING OF COBALT, MANGANESE, IRON AND MAGNESIUM, CONTINUING SAID CONTACTING UNTIL AT LEAST 80% OF THE ALKYLADAMANTANE HAS BEEN OXIDIZED, WHEREBY BRIDGEHEAD DIHYDROXYALKYLADAMANTANE IS FORMED IN SUBSTANTIAL AMOUNT, AND RECOVERING 1,3-DIHYDROXYALKYLADAMANTANE FROM THE REACTION MIXTURE.
 6. METHOD OF PREPARING DIHYDROXYALKYLADAMANTANES WHICH COMPRISES CONTACTING AN ALKYLADAMANTANE SELECTED FROM THE GROUP CONSISTING OF METHYLADAMANTANE, ETHYLADAMANTANE, DIMETHYLADAMANTANE AND METHYLETHYLADAMANTANE WITH A FREE OXYGEN-CONTAINING GAS AT A TEMPERATURE IN THE RANGE OF 110-210*C. AND IN THE PRESENCE OF A SMALL AMOUNT OF OXIDATION CATALYST CONSISTING OF A SOLUBLE HYDROCARBYL CARBOXYLIC ACID SALT OF A METAL SELECTED FROM THE GROUP CONSISTING OF COBALT, MANGANESE, IRON AND MAGNESIUM, SAID CONTACTING BEING EFFECTED IN THE ABSENCE OF A SOLVENT AND UNDER A PRESSURE LESS THAN 100 P.S.I.G., WHEREBY OXIDATION OCCURS TO FORM 1-HYDROXYALKYLADAMANTANE, KETOALKYLADAMANTANE AND A MINOR AMOUNT OF HIGHER BOILING OXIDATION PRODUCTS, STOPPING SAID CONTACTING BEFORE 70% CONVERSION OF THE HYDROCARBON CHARGE AND WHILE THE 1-HYDROXYALKYLADAMANTANE AND KETOALKYLADAMANTANE ARE THE MAIN REACTION PRODUCTS, SEPARATING A CONCENTRATE OF THE LAST-NAMED PRODUCTS FROM SAID HIGHER BOILING OXIDATION PRODUCTS, HYDROGENATING SAID CONCENTRATE TO CONVERT THE KETOALKYLADAMANTANE TO NON-BRIDGEHEAD HYDROXYALKYLADAMANTANE, ISOMERIZING THE HYDROGENATED CONCENTRATE BY CONTACTING SAID CONCENTRATE WITH A CONCENTRATED MINERAL ACID SELECTED FROM THE GROUP CONSISTING OF SULFURIC ACID AND PHOSPHORIC ACID TO CONVERT THE NON-BRIDGEHEAD HYDROXYALKYLADAMANTANE TO ITS BRIDGEHEAD ISOMER, CONTACTING THE ISOMERIZABLE WITH A FREE OXYGEN-CONTAINING GAS AT A TEMPERATURE IN THE RANGE OF 110-210*C. AND IN THE PRESENCE OF A SMALL AMOUNT OF OXIDATION CATALYST AS ABOVE SPECIFIED, WHEREBY BRIDGEHEAD DIHYDROXYALKYLADAMANTANE IS FORMED AS THE MAIN OXIDATION PRODUCT, AND RECOVERING 1,3-DIHYDROXYALKYLADAMANTANE FROM THE REACTION MIXTURE. 